The proposed research includes a study of the enzyme protein carboxyl-methylase which is capable of methylating glutamyl and aspartyl side chain carboxyl groups in protein. The methyl group donor is S-adenosylmethionine. The properties and biological function of the enzyme will be determined in porcine posterior pituitary gland, a tissue which is known to contain the highest level of the "methanol-forming" enzyme of Axelrod and Daley. Evidence indicates the "methanol-forming" enzyme and protein carboxyl-methylase are the same enzyme. Efforts will be made to characterize the normal physiological substrate in posterior pituitary in order to gain insight into the biological function of enzyme in that tissue. The studies are designed to yield information on the structural and kinetic properties of the enzyme, and more importantly the role of the enzyme on the biological processes uniquely associated with the posterior pituitary gland. The enzyme which has the capacity to alter proteif charge, and probably conformation in many instances, has strong implications in the fields of biological regulation and differentiation.